1. Field of the Invention
The present invention relates to an improved piston adapted to be used in a pneumatic, hydraulic, or hydropneumatic installation.
2. The Prior Art
Installations of the type referred to typically include a cylinder, a piston slidably housed within the cylinder and being provided with damping means and being connected to a piston rod, the cavity of the cylinder being filled with gas and/or liquid and being separated by the piston into two working chambers, the piston rod extending through guiding and sealing means provided at one end of the cylinder, and the damping means comprising a constantly open throttled passage between said working chambers.
German Gebrauchmuster No. 7,833,144 describes, for example, a gas spring having a constantly open passage between the working chambers, the passage being defined by a throttled bore through the piston extending parallel to the axis of the piston. This throttled bore is effective only when the piston rod moves out of the cylinder and is adapted to limit the rate of movement of the piston rod out of the cylinder to a predetermined measure. Especially in gas springs having a high internal pressure, these throttled bores have a cross-section of about from 0.3 to 0.4 mm .phi. to achieve the desired damping effect. Due to this narrow cross-section, the bores are susceptible to clogging, as even extremely small impurities can occlude this cross-section. Furthermore, these bores must be made very precisely to maintain the damping effect within the required tolerance.